The object of the invention is a method for treating outlet air in a pneumatic waste conveying system, in which the outlet air is at least partly a conveying air to be used in waste conveying. The method includes the following steps, bringing air in a first phase wherein additional air is brought into a body of conveying air in a partial-vacuum generator of the pneumatic waste conveying system before an output aperture of the partial-vacuum generator and bringing air in a second phase wherein additional air is brought into a body of outlet air as a consequence of a suction effect brought about by the body of outlet air in such a way that the body of outlet air and the additional air at least partly mix with each other.
The object of the invention is also an apparatus for treating outlet air in a pneumatic waste conveying system, in which the outlet air is at least partly a conveying air to be used in waste conveying. The apparatus includes an outward blowing pipe with means for conducting the outlet air into the outward blowing pipe. A partial-vacuum generator includes means for bringing additional air into a body of conveying air in the partial-vacuum generator before an output aperture of the partial-vacuum generator. A means is provided for bringing additional air into a body of outlet air as a consequence of a suction effect brought about by the body of outlet air in such a way that the body of outlet air and the additional air at least partly mix with each other.
The invention relates generally to pneumatic material conveying systems, such as to partial-vacuum transporting systems, more particularly to the collection and conveying of wastes, such as to the conveying of household wastes. Such systems are presented in publications WO 2009/080880, WO 2009/080881, WO 2009/080882, WO 2009/080883, WO 2009/080884, WO 2009/080885, WO 2009/080886, WO 2009/080887 and WO 2009/080888, among others.
Systems wherein wastes are conveyed in piping by means of suction and/or by means of a pressure difference are known in the art. In these, wastes are conveyed long distances in conveying piping. The apparatuses are used for, among other things, the conveying of wastes in different institutions. It is typical to these systems that a partial-vacuum apparatus is used to achieve a pressure difference, in which apparatus a partial vacuum is achieved in the conveying pipe with partial-vacuum generators, such as with vacuum pumps or with an ejector apparatus. A conveying pipe typically comprises at least one valve means, by opening and closing which the replacement air coming into the conveying pipe is regulated. In partial-vacuum conveying systems there are typically noise problems, as well as dust problems and fine particle problems, in the outlet pipe. Especially in waste-transporting systems odor nuisances, which are perceived as unpleasant, often occur in the outlet air. Efforts have been made to reduce odor nuisances by using a liquid-air-ejector as a partial-vacuum generator, the liquid, more particularly liquid mist, functioning as the operating medium of which ejector enhances the suction and binds odors and particles. Some such as these are presented in publications WO 2005/085104, WO 2005/085105 and WO2007/065966, among others. In addition, known in the art are solutions in which a liquid that reduces odor nuisances is brought into the ejector pump. These have functioned fairly well, but they require a certain type of partial-vacuum generator, which is not necessarily suited to all waste-transporting systems.
The aim of the present invention is to achieve an entirely new type of solution in connection with an outward blowing pipe of a waste system, by means of which solution the drawbacks of prior art solutions are avoided. Yet another aim of the invention is to achieve a solution by means of which the odor nuisances of the outlet air of the system as well as possible noise problems in connection with the outward blowing pipe can be decreased. Yet another aim is to enhance the efficiency of the treatment of outlet air in a pneumatic wastes conveying system.